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F A Lemonnier

Publications and source records attributed to F A Lemonnier.

At least 55 records · Page 3Linked to original sources
PubMed1991

Differential regulation of HLA-A3 and HLA-B7 MHC class I genes by IFN is due to two nucleotide differences in their IFN response sequences.

The transcription of HLA-A3 and HLA-B7 class I genes is differentially regulated by IFN-alpha and -gamma, the latter gene being more inducible than the former. To determine the structural basis of this differential response, hybrid genes were constructed in which complete or fragmented HLA-A3 or HLA-B7 promoters were fused to the chloramphenicol acetyl transferase coding sequence. These constructs were tested in transient transfection assays, and the differential response of the HLA-A3 and HLA-B7 genes to IFN was correlated with nucleotide differences in their interferon response sequences (IRS). Replacement of two T nucleotides in the HLA-A3 IRS by the homologous A and C nucleotides of the HLA-B7 IRS was sufficient to impart IFN inducibility of the HLA-A3 promoter and efficient binding of constitutive and IFN-induced nuclear factors to the IRS of HLA-A3. Since the same two nucleotide differences are shared by all sequenced HLA-A and HLA-B genes, these results suggest that high or low responsiveness to IFN might be a locus-related property.

Base Sequence↗
PubMed1991

Differential transcription inducibility by interferon of the HLA-A3 and HLA-B7 class-I genes.

HLA-A3 and HLA-B7 class-I genes are differentially regulated in human T lymphoma Jurkat cells, at the transcriptional level, the expression of the HLA-B7 gene being selectively increased following alpha, beta or gamma interferon (IFN) treatment. Using a series of hybrid CAT constructs, associating HLA-A3 and HLA-B7 complete or fragmented promoters, the differential regulation was shown to be associated with 2 nucleotide differences at positions -176 and -175 in the interferon regulatory sequence (IRS) of the HLA-A3 and the HLA-B7 genes. Replacement, using site-directed mutagenesis, of the 2 thymidine in the HLA-A3-IRS by adenine and cytidine found at the same positions in the HLA-B7-IRS was sufficient to restore IFN inducibility of the HLA-A3 promoter and efficient interaction with HeLa nuclear factors. Since the same nucleotide differences are shared by all sequenced HLA-A and HLA-B class-I genes, the differential induction by IFN of the transcription of the HLA-A3 and B7 genes might be a general locus-related property.

Animals↗
PubMed1990

Beta 2-microglobulin restriction of antigen presentation.

Antigens are generally thought to be recognized by cytotoxic T lymphocytes as peptides in the context of class I major histocompatibility proteins complex, which are heterodimers of heavy chains noncovalently associated with beta 2-microglobulin (beta 2m). The highly polymorphic nature of the heavy chains and their resulting ability to present different sets of peptides has presumably evolved to allow potent immune responses against most pathogens. By contrast, the polymorphism of beta 2m is limited; seven alleles are known in the mouse and only one has been identified in humans. beta 2-Microglobulin was consequently thought to have only structural functions: namely, to ensure correct folding of class I molecules and their transport to the cell surface. Although beta 2m is not implicated directly in the formation of the peptide binding site, we report here that it participates in the selection of MHC class I molecule-associated peptides.

Amino Acid Sequence↗
PubMed1990

Serological analysis of the dissociation process of HLA-B and C class I molecules.

Two forms of HLA class I molecules reacting differentially with the HC-10 monoclonal antibody were identified at the surface of HLA-A3, B7, Cw3 or Cw7 human cells. The HC-10-nonreactive form (which includes all HLA-A3 and a large fraction of HLA-B7, Cw3 and or Cw7 molecules) corresponds to heavy chains apparently tightly associated to beta 2-microglobulin. The HC-10-reactive form (which represents only a fraction of cell surface expressed HLA-B7, Cw3 and Cw7 molecules) corresponds to heavy chains loosely but still associated to beta 2-microglobulin. Further biochemical analyses and the study of mouse transfected cells expressing other HLA class I specificities led to the following conclusions: (a) dissociation of HLA-B and C molecules is a multistep phenomenon, the various stages being identifiable serologically; (b) acquisition of the HC-10 antigenic determinant appears as a hallmark of HLA class I molecules engaged in the process of dissociation; however, its expression does not imply complete separation of heavy and light chains; (c) only the initial stage of the dissociation process can be identified on cell surfaces, whereas (d) following addition of detergent, dissociation of HLA-B and C molecules spontaneously proceeds further, resulting in accumulation in cell lysate of cell surface-derived isolated HLA-B and C class I heavy chains.

Animals↗
PubMed1989

Analysis of the HLA-Cw3-specific cytotoxic T lymphocyte response of HLA-B7 X human beta 2m double transgenic mice.

The cytolytic responses of either normal (non transgenic), HLA-B7 (single transgenic) or HLA-B7 x human beta 2 microglobulin (double transgenic) DBA/2 mice induced by transfected HLA-Cw3 P815 (H-2d) mouse mastocytoma cells were compared, to evaluate whether the expression of an HLA class I molecule in responder mice would favor the emergence of HLA-specific, H-2-unrestricted CTL. Only 8 of 300 HLA-Cw3-specific CTL clones tested could selectively lyse HLA-Cw3-transfected cells in an H-2-unrestricted manner, all having been isolated after hyperimmunization of double transgenic mice. These clones also lysed HLA-Cw3+ human cells. Unexpectedly, the lysis of the human but not that of the murine HLA-Cw3 cells was inhibited by Ly-2,3-specific mAb. Despite significant expression of HLA-B7 class I molecules on transgenic lymphoid cells, including thymic cells, limiting dilution analysis and comparative study of TCR-alpha and -beta gene rearrangements of the eight isolated clones (which suggested that they all derived from the same CTL precursor) indicated that the frequency of HLA-Cw3-specific H-2 unrestricted cytotoxic T lymphocytes remained low (even in HLA-B7 x human beta 2-microglobulin double transgenic mice). This suggests that coexpression of HLA class I H and L chain in transgenic mice is not the only requirement for significant positive selection of HLA class I-restricted cytotoxic mouse T lymphocytes.

Animals↗
PubMed1989

Cytotoxic T lymphocyte recognition of secreted HLA class I molecules.

The cytolytic responses of DBA/2 mice against syngeneic transfected P815 mastocytoma cells expressing either membrane-associated (HLA-Cw3) or -secreted hybrid (HLA-Cw3 x H-2 Q10b) molecules were compared. In spite of the absence of serologically detectable hybrid molecules on their plasma membrane, cells secreting these molecules elicited a CTL response similar to that of cells expressing the membrane associated HLA-Cw3 molecules, in terms of both MHC-restriction and peptide specificity. Together with the observation that syngeneic mice were capable of rejecting the injected secreting cells, these results imply that secreted HLA class I molecules can function as minor histocompatibility Ag and suggest that processing of both the membrane-bound and the -secreted forms of a protein may follow common or overlapping pathways.

Animals↗
PubMed1989

IFN-mediated differential regulation of the expression of HLA-B7 and HLA-A3 class I genes.

The regulation by IFN of the expression of HLA-B7 and HLA-A3 class I molecules was studied in Jurkat human T lymphoma cells, HHK EBV-transformed human B lymphocytes, and murine HLA-B7 HLA-A3 co-transfected L fibroblasts. Jurkat cells express constitutively low level of HLA class I molecules and treatment with human IFN resulted in preferential increase of the expression of HLA-B7 molecules, the expression of the HLA-A3 molecules being relatively unchanged. Similar treatment of HHK cells, which express constitutively large amount of HLA class I molecules, resulted in a marginal increase of the expression of both HLA-B7 and HLA-A3 molecules. HLA-B7 HLA-A3 co-transfected L cells express relatively low level of HLA class I molecules, expression of both however was significantly increased after treatment with murine INF-alpha, the augmentation being more accentuated for HLA-B7 molecules. In all cases, variations of cell surface expression were related to parallel modifications of the level of HLA-B7 and HLA-A3 RNA transcripts. Important nucleotide differences exist between the IFN consensus sequences associated with the HLA-B7 and HLA-A3 class I genes. Using oligonucleotides corresponding to these sequences two patterns of retarded bands were observed by the gel mobility shift assay, suggesting that the IFN-mediated differential regulation of the expression of the HLA-B7 and HLA-A3 genes could be due to different nuclear regulatory factors.

Adjuvants, Immunologic↗
PubMed1989

Antibodies to HLA class I promoter-binding proteins in sera from patients with systemic lupus erythematosus.

Antibodies directed against human cell nuclear factors (HLA-F1 and HLA-F2) that bind to the interferon consensus sequence (ICS) in the promoter region of the HLA-A2 class I gene can be detected in the serum of some patients with systemic lupus erythematosus (SLE). Such antibodies, in gel-shift assays, inhibited the formation of the retarded band corresponding to the HLA-F1/F2-ICS complex irrespective whether purified factors or crude nuclear extracts were used. This inhibitory effect was due to IgG since the SLE serum activity bound to and could be eluted from a protein A-Sepharose column. This effect still persisted after absorption of SLE serum on a DNA-affinity column which removed antibodies directed against protein-free HLA-A2-ICS nucleotide sequence also present in such sera. Western blot analysis further confirmed that SLE serum recognized both HLA-F1 (65 kDa) and HLA-F2 (88 kDa) polypeptides, independently of the presence of the HLA-A2-ICS nucleotidic sequence, as well as other proteins. These results suggest that human sera from some patients with SLE may be used as a convenient source of antibodies directed against DNA-binding proteins regulating gene transcription.

DNA-Binding Proteins↗
PubMed1988

Epitope mapping of HLA-B27 and HLA-B7 antigens by using intradomain recombinants.

To study the HLA-B7 and HLA-B27 antigenic determinants, hybrid genes between these two alleles were constructed by in vivo recombination in Escherichia coli. After transfection of these genes into P815 (high transfection efficiency recipient) murine cells, the bindings of Bw6, HLA-B7, and HLA-B27 allele-specific mAb were studied, as well as that of human anti-HLA-B7 and anti-HLA-B27 monospecific alloantisera. Most of the HLA-B7 antigenic determinants were assigned to the first external domain of the molecule. Four different epitopic areas could be defined: the Bw6 epitope was associated with residues 82 and 83; the BB7.1 epitope to amino acids 63, 67, and 70; the MB40.2 and MB40.3 epitope to amino acid sequence 177-180, and human alloantisera identified as an epitope associated with residue 9. HLA-B27 antigenicity studied by TM-1 mAb was found to involve residues 77 and 80 in the alpha-1 domain. Results obtained with human monospecific alloantisera allowed the definition of an additional allospecific site associated with the NH2 terminal part on the alpha-1 domain of HLA-B27. Epitope mapping fits with data obtained by sequence comparisons and is discussed with reference to the crystallographic three-dimensional structure of the HLA-A2 molecule.

Amino Acid Sequence↗
PubMed1988

Human beta 2-microglobulin specifically enhances cell-surface expression of HLA class I molecules in transfected murine cells.

Sequential transfections of P815 murine mastocytoma cells with class I gene encoding either HLA-Cw3, HLA-A3, or HLA-B7 H chain and subsequently with a human beta 2-microglobulin gene were performed to evaluate the relative efficiency of human and murine beta 2-microglobulins in promoting the cell-surface expression of HLA-class I molecules. A 6-, 11-, and 40-fold specific enhancement of the cell-surface expression of HLA-Cw3, HLA-A3, and HLA-B7 molecules, respectively, was observed in cells co-transfected with human beta 2-microglobulin gene. This effect was attributed to a more efficient association of HLA H chains with human than with murine beta 2-microglobulin, which apparently allowed a more rapid transport of the HLA molecules from the endoplasmic reticulum to the Golgi apparatus.

Animals↗
PubMed1987

Acquisition of HLA class I W6/32 defined antigenic determinant by heavy chains from different species following association with bovine beta 2-microglobulin.

Murine, rat, rabbit and guinea pig class I heavy chains, which do not react with W6/32 monoclonal antibody when they are expressed in association with autologous beta 2-microglobulin (beta 2-m), can acquire such a reactivity once they are expressed at the surface of cells cultured in conditions which allow their association with bovine beta 2-m. Sequence comparison of beta 2-ms suggests that glutamine at position 89 might be critical for the induction of the W6/32 defined antigenic determinant. However, in the murine species, certain class I heavy chains, in spite of their association with bovine beta 2-m, do not express this determinant. Using genetically engineered hybrid class I molecules and selected congenic strains of mice this negative property was shown to be related to the presence of a cysteine residue at position 121 which allows covalent association of beta 2-m to class I heavy chains (Bushkin, Y., J-S. Tung, A. Pinter, J. Michaelson, and E. A. Boyse. 1986. Unusual association of beta 2-microglobulin with certain class I heavy chains of the murine major histocompatibility complex. Proc. Natl. Acad. Sci. USA 83:432). Therefore, expression of the W6/32 defined antigenic determinant implicates both the beta 2-m and the second domain of the heavy chain, but its expression (or exposure) is prevented by the covalent fixation on cysteine 121 of the light chain.

Animals↗
PubMed1987

Creation of an HLA-A2/HLA-Aw69 alloantigenic determinant on an HLA-A3 molecule by site-directed mutagenesis.

The HLA-A2 and HLA-Aw69 molecules share an antigenic determinant not expressed by HLA-Aw68 and HLA-A3. Comparison of the amino acid (aa) sequences of these molecules and previous studies of the antigenic determinant expressed by different HLA-A2 X HLA-A3 hybrid molecules had established that three aa at positions 95, 97, and 107 were possibly involved in the formation of this determinant. The HLA-A3 gene was therefore mutagenized to replace successively at these positions the HLA-A3-specific aa by the HLA-A2 residues. A single substitution at position 107 of a glycine by a tryptophan residue is sufficient for full expression by HLA-A3 molecules of the HLA-A2/Aw69 shared antigenic determinant without modification of the other serological reactivities characteristic of the HLA-A3 molecules. Previous studies of ethyl methanesulfonate mutants having shown the involvement of aa 161 in this determinant, we assume that the two aa residues 107 and 161 are close to each other.

Amino Acid Sequence↗
PubMed1986

Transfection of murine LMTK- cells with purified HLA class I genes. VII. Association of allele- and locus-specific serological reactivities with respectively the first and second domains of the HLA-B7 molecule.

The individual contributions of the first two external domains of the HLA-B7 heavy chain to the expression of allele-specific (B7) and locus-specific (B and C) antigenic determinants were investigated using hybrid class I genes. Hybrid genes were constructed in vitro by exon shuffling between the parent genes HLA-B7, HLA-Cw3, HLA-A3, and H-2Kd, and their expression was monitored following transfection into mouse L cells. The results show that most allele-specific antigenic determinants are associated with the first external domain of the B7 heavy chain, whereas all the locus-specific antigenic determinants tested map to the second external domain.

Animals↗
PubMed1985

Analysis of the expression of cloned HLA class I genes in mouse transfected L cells by quantitative flow cytometry.

By using a calibrated cell sorter and monoclonal antibodies conjugated to fluorochromes, a quantitative analysis of the levels of expression of HLA class I molecules at the surface of cloned murine L cells transfected with purified A3, B7, or CW3 genes was performed and compared with radioimmunoassay data. We selected clones of heterogeneous levels of HLA class I expression, which were shown to remain constant over a period of 4 mo in absence of HAT selection and not to be correlated to the DNA copy number of the corresponding integrated gene.

Animals↗
PubMed1985

Altered structure of HLA class I heavy chains associated with mouse beta-2 microglobulin.

The serological reactivities of HLA-A3, -B7, and -CW3 heavy chains associated with either mouse, bovine, or human beta-2-microglobulin (beta 2m) and expressed on the surface of transfected mouse fibroblasts were analyzed. All reactivities associated with one cluster (defined by monoclonal antibody W6/32) of antigenic determinants expressed by these HLA class I molecules were lost, or profoundly reduced, after each heavy chain associated with mouse beta 2-m. Expression by the transfected fibroblasts of the HLA-A3, -B7, and -CW3 heavy chains in association with human beta 2m restores these reactivities. Since most of the amino acid differences between mouse and human beta 2m probably correspond to externally oriented hydrophilic residues, these results suggest that critical interactions in the three-dimensional structure of HLA class I molecules occur between the light chain and the first two external domains of the class I heavy chains, to which some of the altered reactivities have been mapped.

Animals↗
PubMed1985

Expression of an HLA-Bw6-related specificity by the HLA-Cw3 molecule.

Radioimmunoassay of HLA-transformed mouse L cells expressing A3, A24, B7, or Cw3 HLA class I molecules with a set of monomorphic monoclonal antibodies distinguishes between A3-A24 and B7-Cw3 patterns of reactivity. Analyses with Bw6-specific monoclonal antibodies and a human alloantiserum demonstrate the expression by the HLA-Cw3 molecules of a Bw6 public specificity related to but not identical with that expressed by the HLA-B7 molecules. Exon-shuffling experiments and inhibition studies of monoclonal antibody cell-surface fixation indicate that similar parts of B7 and Cw3 molecules account for their serological cross-reactivity.

Animals↗